Polysiloxane polymers, especially polysiloxane polymers containing sulfur atoms are described in U.S. Pat. No. 4,046,795 to Martin, in which a disiloxane and/or a hydrocarbonoxy or hydroxy containing silane or siloxane is reacted with a cyclic trisiloxane in the presence of an acid catalyst, in which at least one of the above organosilicon compounds contain an R'(SR"').sub.y group, in which R' is a divalent, trivalent or tetravalent hydrocarbon radical, R"' is hydrogen or a monovalent hydrocarbon radical and y is a number of from 1 to 3. The resultant polysiloxane polymers contain MDT' structural units in which M represents an R.sub.3 SiO.sub.0.5 unit, D represents an R.sub.2 SiO unit and T' represents a unit of the formula (R"'S).sub.y R'SiO.sub.1.5, in which R, R' and R"' are the same as above.
Compared to the polysiloxane polymers described in the above patent, the polysiloxane polymers of the present invention contain (M).sub.x (T').sub.y structural units instead of the MDT' units. Polysiloxane polymers which are free of the "D" units have certain advantages over polysiloxanes containing "D" units. For example, the polysiloxanes of this invention which are free of the "D" units are more compatible with organic compounds while retaining some of the silicon compound characteristics. Moreover, the polysiloxane polymers of this invention may be reacted with cyclic siloxanes such as octaorganocyclotetrasiloxanes to form polysiloxane polymers containing "D" units.
Also, U.S. Pat. No. 3,794,672 to Kim describes perfluoroalkyl silicon compounds containing sulfur which are prepared by reacting olefins of the formula R.sub.f CH.dbd.CH.sub.2 with a silicon compound of the formula ##EQU1## in the presence of free radical generators, such as peroxides, in which R.sub.f is a perfluoroalkyl radical, R is an alkylene radical, X is chlorine, acetoxy or an alkoxy radical, n is 0 to 2, and m is 0 to 3 and the sum of n+m is not greater than 3.
In contrast to the teachings of Kim, it has been found that polysiloxane polymers having (M).sub.x (T').sub.y structural units can be prepared by reacting a disiloxane with a mercapto- or thiofunctional trihydrocarbonoxysilane.
Therefore, it is an object of the present invention to provide polysiloxane polymers which are more compatible with organic compounds while retaining some of the characteristics of the silicon compounds. Another object of this invention is to provide polysiloxane polymers which are free of the "D"(R.sub.2 SiO) units. Still another object of this invention is to provide polysiloxane polymers which may be used as crosslinking agents in free-radical polymerizations. A further object of this invention is to provide a method for preparing polysiloxane polymers which are free of "D" (R.sub.2 SiO) units.